A rectangle of Tyvek, cut from an oversized envelope, works fantastically as a windstopper when shoved down the front of one’s jersey. Especially in the pissing rain. Packs super small, and is waterproof as well

Angeles Crest climb, versus the Big Tujunga descent. Wet and foggy up, totally dry and clear down. Four seasons in one day! Luckily I had packed my windstopper cut from a USPS envelope… well, it worked